Montessa could be considered a variant spelling of Montesa. This appears to have been the name of a fortified stronghold in Spain (Kingdom of Aragon) in the Middle Ages.

The name was adopted by a Catholic military order, The Order of Montesa, which succeeded the disbanded Knights Templar in Spain in the early 1300's. The order survived into the 20th century, altho it may no longer be active.

Montesa is best known as a popular brand of Spanish motorcycle, which was successful in racing and was bought out by Honda in the 1980's. The motorcycle got its name from the military order.

Hope this is of some help, altho it may not have been what your parents had in mind.